Lithium metal composite oxide powder with suppressed gas generation

Abstract

A lithium metal composite oxide powder for use in a positive electrode active material for a lithium ion battery has a composition of Li a Ni b Co c Al d O 2 (wherein, a=0.8 to 1.2, b=0.7 to 0.95, c=0.02 to 0.2, d=0.005 to 0.1, and b+c+d=1). The powder has been treated with an aqueous solution of an organic metal salt and soluble aluminum salt and does not cause volume expansion due to gas generation. A positive electrode active material with the lithium metal composite oxide powder has a large discharge capacity, excellent cycle characteristics, and suppressed gas generation.

The invention claimed is: 
     
         1 . A lithium metal composite oxide powder for use in a positive electrode active material for a lithium ion battery, the powder having a composition of Li a Ni b Co c Al d O 2 , wherein a=0.8 to 1.2, b=0.7 to 0.95, c=0.02 to 0.2, d=0.005 to 0.1, and b+c+d=1, the powder having been treated with an aqueous solution comprising an organic metal salt and a water-soluble aluminum salt and then dried at a temperature of about 300° C. to 700° C., wherein the organic metal salt of the aqueous solution comprises Na or K as the metal. 
     
     
         2 . The lithium metal composite oxide powder according to  claim 1 , wherein aluminum agglomeration is not observed by energy dispersion type X-ray analysis. 
     
     
         3 . The lithium metal composite oxide powder according to  claim 1 , whereby the organic metal salt is a metal acetate. 
     
     
         4 . The lithium metal composite oxide powder according to  claim 1 , whereby the organic metal salt is a surfactant. 
     
     
         5 . The lithium metal composite oxide powder according to  claim 1 , comprising a LiOH content of 0.5 wt. % or lower. 
     
     
         6 . The lithium metal composite oxide powder according to  claim 1 , whereby the organic metal salt has at least three carbon atoms per metal atom. 
     
     
         7 . The lithium metal composite oxide powder according to  claim 1 , wherein the organic metal salt comprises Na as the metal. 
     
     
         8 . The lithium metal composite oxide powder according to  claim 1 , wherein the water-soluble aluminum salt is aluminum sulfate. 
     
     
         9 . A method for preparing the lithium metal composite oxide powder of  claim 1  for use in a positive electrode active material for a lithium ion battery, comprising a first step of preparing a preliminary lithium metal composite oxide powder having a composition of Li a Ni b Co c Al d O 2 , wherein a=0.8 to 1.2, b=0.7 to 0.95, c=0.02 to 0.2, d=0.005 to 0.1, and b+c+d=1, a second step of treating said preliminary lithium metal composite oxide powder with an aqueous solution of an organic metal salt and a water-soluble aluminum salt, and a third step of drying the treated preliminary lithium metal composite oxide powder at a temperature of about 300° C. to 700° C. 
     
     
         10 . A method according to  claim 9 , wherein the organic metal salt is a metal acetate or has at least three carbon atoms per metal atom. 
     
     
         11 . A method according to  claim 9 , wherein the organic metal salt is a surfactant. 
     
     
         12 . A lithium ion battery having a positive electrode active material containing the lithium metal composite oxide powder according to  claim 1 .